Cannabis Hyperemesis Syndrome: Symptoms, Causes and Treatment

What is cannabis hyperemesis syndrome?

Cannabis hyperemesis syndrome, also called cannabinoid hyperemesis syndrome or CHS, is a pattern of repeated vomiting episodes linked to regular cannabis use.¹ Hyperemesis simply means severe vomiting.

It is a strange condition on the face of it, because cannabis is better known for easing nausea. CHS was first described in 2004, and case reports have multiplied since.²

The Alcohol and Drug Foundation describes it as rare, and more likely with heavy, long-term smoking of high-THC cannabis.³ It may be under-recognised. In a survey at a United States emergency department, about a third of people who smoked cannabis at least 20 days a month reported symptoms that fitted the pattern.⁴

Symptoms

A review that pooled 183 published reports found these features in people diagnosed with CHS:¹

• Bouts of nausea and vomiting that come and go, in everyone
• Stomach pain, in 85 per cent
• Relief from hot showers or baths, in 92 per cent
• Symptoms going away after stopping cannabis, in 97 per cent

The vomiting comes in cycles, with spells in between. Because cannabis is widely used to settle nausea, the link is easy to miss.²

The hot shower clue

Compulsive hot bathing is the feature most closely associated with CHS. In a series of 98 patients at one hospital, 91 per cent of those who were asked said hot showers or baths eased their symptoms.⁵ Nobody knows why it helps, and it is not unique to CHS, so it cannot confirm the diagnosis by itself.^1,2

Who gets it?

• Regular users. Almost everyone in the pooled reports, 97 per cent, used cannabis at least weekly.¹
• Long-term users. In the hospital series, most people had used cannabis for more than two years before the vomiting started.⁵
• Younger adults. Every patient in that series was under 50.⁵
• More men than women. About 73 per cent of reported cases were in men.¹

What causes CHS is still unclear.¹ Researchers also disagree about how to define it, and about whether cannabis causes the vomiting outright or brings out an underlying tendency to cyclic vomiting.²

How is it diagnosed?

There is no test for CHS. A doctor makes the diagnosis from the pattern: repeated vomiting episodes, regular cannabis use, and no other explanation.⁵ Diagnostic criteria exist, although experts have pointed out their limits.²

Because repeated vomiting has many causes, some of them serious, you may need blood tests and other investigations to rule those out.⁶ The strongest confirmation comes later, if the episodes stop once cannabis is stopped.¹

Tell the doctor how much cannabis you use and how often. It is the piece of information the diagnosis depends on.

Treatment

During an episode

Hospital treatment is mostly supportive. Fluids through a drip treat dehydration, and doctors may try medicines for nausea or a chilli-based cream rubbed on the skin of the abdomen.^1,7

The usual anti-nausea medicines often do not work well in CHS, and high-quality evidence for any medicine is limited.⁷ Strong opioid painkillers are best avoided.¹

Stopping cannabis

Stopping cannabis is the treatment that works.¹ In the hospital series, six of the seven people who were followed up after quitting had no further symptoms.⁵

Getting through the first weeks

Stopping after regular use can bring withdrawal. In a review of 47 studies of people with regular or dependent cannabis use, 47 per cent had withdrawal symptoms.⁸ These can include cravings, trouble sleeping, low or anxious mood, changes in appetite, restlessness and nausea. They are usually at their worst 1 to 4 days after quitting and may last about 3 weeks.⁹

Support helps. Talking therapies such as cognitive behavioural therapy can substantially reduce cannabis use and the problems that come with it.¹⁰ The National Alcohol and Other Drug Hotline offers free, confidential advice on 1800 250 015.¹¹

What if my cannabis is prescribed?

CHS has been reported with regular cannabis use of any duration.¹ If you take a prescribed product that contains THC and you develop repeated nausea or vomiting, tell your prescriber. Nausea and vomiting are also listed side effects of medicinal cannabis in general.¹¹

When it can't wait

Go to an emergency department or call 000 if you:⁶

• Vomit blood, or vomit that looks like coffee grounds
• Vomit green bile
• Have severe or constant stomach pain
• Have chest pain, a severe headache, or a stiff neck with a fever

Get medical help the same day if you are vomiting and you have signs of dehydration, cannot keep water down, or it has gone on for more than 48 hours.⁶

When to talk to a doctor

• You use cannabis regularly and keep having bouts of vomiting or stomach pain
• You notice that hot showers are the only thing that helps
• You want help to stop or cut down

References

1. Sorensen CJ, DeSanto K, Borgelt L, et al. Cannabinoid Hyperemesis Syndrome: Diagnosis, Pathophysiology, and Treatment-a Systematic Review. J Med Toxicol. 2017;13(1):71-87.
2. Venkatesan T, Levinthal DJ, Li BUK, et al. Role of chronic cannabis use: Cyclic vomiting syndrome vs cannabinoid hyperemesis syndrome. Neurogastroenterol Motil. 2019;31 Suppl 2(Suppl 2):e13606.
3. Alcohol and Drug Foundation. Cannabis (THC).
4. Habboushe J, Rubin A, Liu H, et al. The Prevalence of Cannabinoid Hyperemesis Syndrome Among Regular Marijuana Smokers in an Urban Public Hospital. Basic Clin Pharmacol Toxicol. 2018;122(6):660-662.
5. Simonetto DA, Oxentenko AS, Herman ML, et al. Cannabinoid hyperemesis: a case series of 98 patients. Mayo Clin Proc. 2012;87(2):114-9.
6. healthdirect. Vomiting.
7. Richards JR, Gordon BK, Danielson AR, et al. Pharmacologic Treatment of Cannabinoid Hyperemesis Syndrome: A Systematic Review. Pharmacotherapy. 2017;37(6):725-734.
8. Bahji A, Stephenson C, Tyo R, et al. Prevalence of Cannabis Withdrawal Symptoms Among People With Regular or Dependent Use of Cannabinoids: A Systematic Review and Meta-analysis. JAMA Netw Open. 2020;3(4):e202370.
9. healthdirect. Cannabis (marijuana).
10. Connor JP, Stjepanović D, Le Foll B, et al. Cannabis use and cannabis use disorder. Nat Rev Dis Primers. 2021;7(1):16.
11. healthdirect. Medicinal cannabis.